Partitive articles & de

Three things to internalise. One: the partitive expresses an UNSPECIFIED AMOUNT — "some", "any". Je mange du pain = I eat (some) bread. Je fais de la natation = I do (some) swimming. The four forms match the noun's gender, number, and whether it starts with a vowel: du (m. consonant), de la (f. consonant), de l' (vowel/silent h, any gender), des (plural, any gender). Two: under negation, all four collapse to de (or d' before vowels). Je fais du sport → Je ne fais pas DE sport. Je mange des frites → Je ne mange pas DE frites. Three: don't confuse the partitive (du, de la) with the contractions of à (au, à la). They look similar but mean different things: au cinéma = TO the cinema (destination); du cinéma = OF / FROM the cinema (origin or partitive).